Advances towards the complete in vitro life cycle of Toxoplasma gondii

Abstract

The full life cycle of Toxoplasma gondii cannot be recapitulated in vitro , and access to certain stages, such as mature tissue cysts (bradyzoites) and oocysts (sporozoites), traditionally requires animal experiments. This has greatly hindered the study of the biology of these morphologically and metabolically distinct stages, which are essential for the infection of humans and animals. However, several breakthrough advances have been made in recent years towards obtaining these life stages in vitro , such as the discovery of several molecular factors that induce differentiation and commitment to the sexual cycle, and different culture methods that use, for example, myotubes and intestinal organoids to obtain mature bradyzoites and different sexual stages of the parasite. We review these novel tools and approaches, highlight their limitations and challenges, and discuss what research questions can already be answered with these models. We finally identify future routes for recapitulating the entire sexual cycle in vitro .

Public Health Significance of Human Toxoplasmosis

“…Researchers discovered that cats and other felines are the definitive hosts of Toxoplasma, meaning that the protozoa can complete their sexual reproduction cycle only in their intestines. They shed Toxoplasma oocysts in their feces, which can contaminate the environment and serve as a source of infection for other animals [33].…”

“…In any case, Toxoplasma remains a vigorous field of research nowadays, with continuing efforts to further resolve its complex life cycle, host-parasite interactions, and the development of improved diagnostic methods and therapeutic interferences. Its historical points have shaped our understanding of the protozoan and progress to inform attitudes toward the prevention and control of Toxoplasmosis [33].…”